Mining Novel Effector Proteins from the Esophageal Gland Cells ofMeloidogyne incognita

Abstract

Meloidogyne incognita is one of the most economically damaging plant pathogens in agriculture and horticulture. Identifying and characterizing the effector proteins, which M. incognita secretes into its host plants during infection, is an important step towards finding new ways to manage this pest. In this study we have identified the cDNAs for 18 putative effectors, i.e., proteins that have the potential to facilitate M. incognita parasitism of host plants. These putative effectors are secretory proteins that do not contain transmembrane domains and whose genes are specifically expressed in the secretory gland cells of the nematode, indicating that they are likely secreted from the nematode through its stylet. We have determined that in the plant cells, these putative effectors are likely to localize to the cytoplasm. Furthermore, the transcripts of many of these novel effectors are specifically up-regulated during different stages of the nematode’s life cycle, indicating that they function at specific stages during M. incognita parasitism. The predicted proteins showed little to no homology to known proteins from free-living nematode species, suggesting that they evolved recently to support the parasitic lifestyle. On the other hand, several of the effectors are part of gene families within the M. incognita genome as well as that of Meloidogyne hapla, which points to an important role that these putative effectors are playing in both parasites. With the discovery of these putative effectors we have increased our knowledge of the effector repertoire utilized by root-knot nematodes to infect, feed, and reproduce on their host plants. Future studies investigating the roles these proteins play in planta will help mitigate the effects of this damaging pest.

TheDitylenchus destructorgenome provides new insights into the evolution of plant parasitic nematodes

“…Protein sequences of effectors reported in the root-knot and cyst nematodes [34][35][36][37] were obtained from GenBank. Blast was used to predict putative homologous effectors from D. destructor.…”

Transcriptome analysis of root‐knot nematode (Meloidogyne incognita)‐infected tomato (Solanum lycopersicum) roots reveals complex gene expression profiles and metabolic networks of both host and nematode during susceptible and resistance responses

“…The majority of effector molecules are produced in the oesophageal glands (two subventral and one dorsal), whereas others are synthesized in the hypodermis and amphids. Effectors have been identified using various approaches, such as expressed sequence tag (EST) or genomic datasets and direct sequencing of gland cell mRNA (Bellafiore et al, 2008;Huang et al, 2003;Rutter et al, 2014a). A number of RKN effectors, including cellulases, xylanases, annexins, expansins, calreticulin, fatty acid retinolbinding (FAR) protein and chorismate mutase, have been characterized previously Huang et al, 2005;Jaouannet et al, 2013;Jaubert et al, 2005;Truong et al, 2015).…”

Dual RNA‐seq reveals Meloidogyne graminicola transcriptome and candidate effectors during the interaction with rice plants

“…In another study performed on M. incognita , Rutter et al . () sequenced specific mRNAs isolated from gland cells dissected at several parasitic stages and identified 18 putative effectors by a combination of in silico and molecular approaches. Similar strategies have also been employed to discover novel effectors from the recently sequenced genome of the cyst nematode Globodera pallida .…”

“…Genome data mining of M. incognita and Meloidogyne hapla, the two Meloidogyne genomes sequenced so far Opperman et al, 2008), combined with RNA-silencing experiments, has enabled the validation of 12 novel effector genes involved in M. incognita parasitism (Danchin et al, 2013). In another study performed on M. incognita, Rutter et al (2014a) sequenced specific mRNAs isolated from gland cells dissected at several parasitic stages and identified 18 putative effectors by a combination of in silico and molecular approaches. Similar strategies have also been employed to discover novel effectors from the recently sequenced genome of the cyst nematode Globodera pallida.…”